Debt and Other Financing Arrangements - Narrative (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018
Line Of Credit Facility [Line Items]
Credit Agreement	$ 45,000,000.0	$ 45,000,000.0	$ 18,000,000.0
Line of Credit Facility, Remaining Borrowing Capacity	155,000,000.0	$ 155,000,000.0
Line of Credit Facility, Expiration Year And Month		2022-10
Receivables facility amount outstanding	141,500,000	$ 141,500,000	176,600,000
Letters of Credit Outstanding, Amount	10,100,000	10,100,000
Receivables Facility Remaining Borrowing Capacity	0	0
Receivables Facility Maximum Borrowing Availability	151,600,000	151,600,000
Receivables facility maximum borrowing capacity	$ 225,000,000.0	225,000,000.0
Accounts Receivable Facility, Renewal Term	364 days
Accounts Receivable Facility, Expiration Year And Month	2021-05
Accounts Receivable Sold		20,200,000
Other Installment Financing Arrangements	$ 43,700,000	43,700,000	44,600,000
Other Liabilities, Current	44,500,000	44,500,000	39,200,000
Data Center Financing Arrangements [Member]
Line Of Credit Facility [Line Items]
Other Installment Financing Arrangements	4,400,000	4,400,000	4,500,000
Pole license agreement obligation [Member]
Line Of Credit Facility [Line Items]
Other Installment Financing Arrangements	39,300,000	39,300,000	40,100,000
Other Liabilities, Current	$ 1,000,000.0	$ 1,000,000.0	$ 1,000,000.0